title: Phase coexistence in manganites: doping and structural dependence.
abstract: We present a study on the phase coexistence (PC) of paramagnetic insulating (PM-I) and ferromagnetic metallic (FM-M) phases in the La(1- y)(Ca(1-x)Sr(x))(y)MnO(3) system with 0.23 ≤ y ≤ 0.45. The study was performed by means of magnetization and electron spin resonance (ESR) measurements. At high temperatures the ESR spectrum consists of a single symmetric PM line. At T(C), a FM asymmetric line is observed shifted to low fields. In a ΔT temperature range both lines are visible, defining a range of PC. For x = 0, we obtained ΔT as a function of the carrier concentration y, finding that the largest ΔT corresponds to y = 0.25. For this y value, the extreme compounds are orthorhombic and rhombohedral for x = 0 and 1, respectively. The rhombohedral to orthorhombic temperature transition (T(RO)) was determined as a function of x. We found that [Formula: see text] only if T(C) < T(RO). The PM-I/FM-M phase coexistence was only observed in the orthorhombic phase while seems to be incompatible with the more symmetric rhombohedral phase.
authors.affiliation: Centro Atómico Bariloche, 8400 San Carlos de Bariloche, Río Negro, Argentina. galejand@cab.cnea.gov.ar
authors.forename: G
authors.initials: G
authors.lastname: Alejandro
authors.forename: M
authors.initials: M
authors.lastname: Otero-Leal
authors.forename: M
authors.initials: M
authors.lastname: Granada
authors.forename: D
authors.initials: D
authors.lastname: Laura-Ccahuana
authors.forename: M
authors.initials: M
authors.lastname: Tovar
authors.forename: E
authors.initials: E
authors.lastname: Winkler
authors.forename: M T
authors.initials: MT
authors.lastname: Causa